Continuous casting mold



Aug. 31, 1965 A, BUNGEROTH ETAL 3,203,055

CONTINUOUS CASTING MOLD Original Filed March 11, 1960 WWW/1,.

Aug. 31, 1965 A, BUNGEROTH ETAL 3,203,055

CONTINUOUS CASTING MOLD Original Filed March 11, 1960 mwemors Ado/f Synge/0m E/W/n Smeufe/e By fhe/r af/omeys MM o.

United States Patent 3,203,055 CONTINUOUS CASTING MOLD Adolf Buugeroth, Duishurg-Huckingen, and Erwin 'Scheufele, Duisburg-Ungelsheim, Germany, assignors to Mannesmann Aktiengesellschaft, Dusseldorf, Germany, a German company Continuation of application Ser. No. 14,368, Mar. 11, 1960. This application Dec. 24, 1962, Ser. No. 248,833 6 Claims. (Cl. 22--57.2)

This is a continuation of U.S. application Serial Number 14,368 filed March 11, 1960, now abandoned. The invention relates to a mold for continuous casting. Experience during continuous casting of molten metallic material, especially iron and steel, has taught that the question of durability of the molds is less a question of direct wear than it is a question of the resulting deformations. These deformations are the consequence of tensions released during the elimination of heat from the molten material through the mold wall because of the inherent temperature-gradient in the mold wall as well as the variable wall temperatures due to circumference and length of the mold.

Besides changes in the cross-section, i.e. profile, these deformations become especially objectionable in the many types of molds composed of separate walls or wall parts for the reason that they produce splitting at the bumping edges. The molten material enters into these split bumping edges, and cool-s off quickly. Thus satisfactory release of the casting is prevented. This may go so far that the casting is caught and tearing occurs.

Such deformations do not make the mold wholly useless. However, they make necessary the disassembling of the mold and the correction of its walls. Having this mold out of use involves additional work, time and cost. The known alternatives of special clamping of the mold and walls, suitable bumping edge construction, etc. have been only partially successful.

The invention prevents the tensions, which are the unavoidable consequence of the temperature-gradient in the mold wall, from causing greater deformation-s. For this purpose slits are sawed from the outside into the mold in a direction transverse to the lengthwise mold axis. The slits are formed vertically and horizontally into a grid-like pattern .and may be 40 mm. deep in a mold wall having a 50 mm. thickness. This leaves the innermost 20% or 10 mm. of the wall-entirely unslit. The unslit portion of the wall is the plate portion. The outer 80% of the wall is divided into a column portion and a frame portion. The column portion comprises columns which are rectangular in cross section and which are separated from each other both horizontally and vertically by the slits. Surrounding the column portion is the frame portion which remains entirely unslit and forms a peripheral rim around the column portion. The cross sectional width of the columns should not exceed 50 mm. and their cross sectional height should not exceed 150 mm. Thus the slits are never separated by horizontal and vertical distances of more than 50 mm. and 150 mm. respectively. The spacing between the columns themselves is very small. Thus in the example shown in the drawing, to be described hereinafter, the spacing as compared to the 10 mm. thickness of the plate portion of the wall is shown to be 2 mm. or less. Thus the slits may be 2 mm. wide and 40 mm. deep in a plate 50 mm. thick. It can be seen from this that the slits are so narrow that circulation of cooling water which may be present in these slits is almost impossible. This helps to ensure that the temperature drop over the entire thickness of the .wall is not substantially disturbed.

Since the temperature drop in the mold wall is largest in the region of the surface of the molten metal and becomes "ice continuously smaller toward the lower end of the mold due to the formation of an .air gap between the casting surface and the inner surface of the mold wall, the interval between the slits at the lower part of the mold wall can be made larger than the interval between the slits at the upper part of the mold where the metal is more molten. The case applies to the circumference of the mold since the temperature gradient is greatest in the middle of the wall.

Assuming that under normal circumstances there exists a temperature drop of approximately 200 C. over the thickness of the plate, a temperature-gradient of only about 40 C. would now occur in the 10 mm. section of wall remaining unslit as per the example cited above. The total mold wall may now mechanically be looked upon as a thin 10 mm. wide plate wherein occurs only a minimum temperature drop and wherein, as a consequence, there will develop only very inconsequential tensions. These tensions, because of the temperature gradient will cause only a small inconsequential distortion of the plates.

The deformations occuring in the various rectangular columns are unable to influence each other, because they cannot add up or accumulate. Thus the slits operate pr-actically like a joint. The produced tensions arising out of the variable temperature distribution over the length of the mold and the mold circumference, respectively, and the deformations caused thereby, are also reduced by the slits. This generally reduces to a minimum the deformation of a mold and the various plates, substantially increasing the operational life of the mold.

It has proved of special advantage to fill in the slits with flexible material having a heat retentiv-ity greater than that forming the mold, as for instance graphite in cases where deformations directed to the outside (tending to create convex surfaces of the exterior or water sides of the mold walls) are expected. Such graphite in a yielding or plastic state is indicated in two slots in FIG. 1 and the two slots in FIG. 4 by the reference character 14. However, if deformations are directed toward the inside, into the mold space (tending to create concave surfaces of the exterior or water sides of the mold walls), it is recommended that strip-like inlays 15, see FIG. 5, consisting of material, suchas sheet metal, having a thermal conductivity lower than (that is, a heat retentivity greater than) that of the mold material, be inserted in the slits 10.

The cooling of the mold according to the invention and its walls is effected by means of superimposed cooling boxes, which cover the slit middle part of the walls and are fastened to the unslit frame (see FIG. 1).

The drawings show an example of a four cornered mold composed of plates according to the invention.

FIG. 1 shows a horizontal cross-section through one corner of a mold made in accordance with the invention.

FIG. 2 is a view in elevation of a vertical mold wall shown in part in FIG. 1, here shown from the outside, partly broken away.

FIG. 3 is a schematic diagram showing plate deformations occurring without and with the use of the invention.

FIG. 4 is a view on an enlarged scale of two of the slits in FIG. 1 containing graphite in a plastic or flexible state.

FIG. 5 is a view on an enlarged scale of two of the slits in FIG. 2 containing sheet metal strips.

As shown in FIG. 1 the abutting mold walls 2 and 4 are provided with deeply cut-in slits 10. These cover the area of the mold with the exception of unslit rim areas 6 and 8. The slits 10 are open toward the outside. These slits are arranged horizontally as well as vertically and in the example presented a depth of about four-fifths of the wall thickness is shown. The slits 10 are covered with cooling boxes 12 fastened in the slitless areas 6 and 8 with a cooling liquid circulating in the boxes. In the case of one piece chill molds the corners also may be provided with slits and for cooling a closed surrounding water jacket may be provided. This may also be used in circular molds.

-FIG. 3 shows a schema-tic presentation of part of a mold wall, i.e. a mold wall plate. In an unslit condition deformations may occur which, cumulatively, may amount to approximately the height and size of the outer are A. With slits 10 such as those of FIGS. 1 and 2 occurring in greater frequency than in the unslit wall the expansion and depth of the deformations B will multiply. However, due to the lack of mass, they will not attain the size of the first-shown deformation A. Since the placed slits are effective as a joint, they cannot add up, i.e. accumulate. The effect of the invention shows most clearly Where the slits 100 are arranged in intervals as close to each other as possible with resulting deformations which correspond approximately to the arcs C. It goes without saying that the deformations only rarely assume the form of an even arc, such as shown in the schematic drawing. The drawing is merely to show the effect of the measures taken according to the invention.

FIG. 4 shows a horizontal cross-section of the mold Wall 4 with the slits 10 filled with graphite 14 and a cooling box 12 on the outside of the mold wall 4.

FIG. shows a horizontal cross-section of a mold wall with the slits being indicated and filled with metal strip-like inlays 15.

What is claimed is:

1. A continuous casting mold for the casting of molten material, especially iron and steel, having planar mold walls with a decreasing temperature gradient Within the walls from inside to outside when in use, each mold wall comprising a plate portion, a frame portion integral with said plate portion and a portion having spaced rectangular columns also integral with said plate portion, said frame portion surrounding said column portion and extending outwardly from said plate portion a distance substantially in excess of the thickness of said plate portion, said column portion extending outwardly the same distance and comprising a plurality of rectangular columns positioned in vertical and horizontal rows and spaced from each other a distance which is substantially less than the thickness of said plate portion, the spacing between said columns being such that cooling water could hardly circulate therein even if said spacing were not filled with solid material, said spacing being filled with a solid yielding heat retaining material; whereby the temperature gradient across the inside to outside dimension of the mold wall remains substantially constant and said yielding material absorbs deformations in said columns due to the temperature gradient in the mold wall there-by stopping deformations from accumulating from one column to another and from one part of the mold wall to another.

2. A continuous casting mold according to claim '1 wherein the solid flexible heat-retaining material filling 4- the spacing between the columns is a graphitic plastic material.

3. A continuous casting mold according to claim 1 wherein the solid flexible heat-retaining material filling the spacing between the columns is a multiplicity of striplike inlays made of a material of lower thermal conductivity than the mold.

4. A continuous casting mold for the casting of molten material, especially iron and steel, having planar mold walls with a decreasing temperature gradient within the walls from inside to outside when in use, each mold wall comprising a plate portion, a frame portion integral with said plate portion and a portion having spaced rectangular columns also integral with said plate portion, said frame portion surrounding said column portion and extending outwardly from said plate portion a distance approximately 4 times as great as the thickness of said plate portion, said column portion extending outwardly the same distance and comprising a plurality of rectangular columns positioned in vertical and horizontal rows spaced from each other a distance which is about one-fifth the thickness of said plate portion, the spacing between said columns being such that cooling water could hardly circulate therein even if said spacing were not filled with solid material, said spacing being filled with a solid yielding heat retaining material; whereby the temperature gradient across the inside to outside dimension of the mold wall remains substantially constant and said yielding material absorbs deformations in said columns due to the temperature gradient in the mold wall thereby sto ping deformations from accumulating from one column to another and from one part of the mold wall to another.

5. A continuous casting mold according to claim 4 wherein the solid flexible heat-retaining material filling the spacing between the columns is a graphite plastic material.

6. A continuous casting mold according to claim 4 wherein the solid flexible heat reta-ining material filling the spacing 'between the columns is a multiplicity of striplike inlays made of a material of lower thermal conductivity than the mold.

References Cited by the Examiner UNITED STATES PATENTS 679,743 8/01 Gorman 22.-177

921,972 5/09 Gathmann 22177 1,910,015 5/33 Homand 22-177 2,097,637 I l/37 Osolin 26639 2,169,893 8/39 Crampton et al 2257.2 2,480,359 8/49 Debenham 266-39 2,526,687 10/50 Reams 266-39 2,747,244 5/56' Goss 22-572 I. SPENCER OVERHOLSER, Primary Examiner.

ROBERT F. WHITE, MICHAEL V. BRINIDIS I,

Examiners. 

4. A CONTINUOUS CASTING MOLD FOR THE CASTING OF MOLTEN MATERIAL, ESECIALLY IRON AND STEEL, HAVING PLANAR MOLD WALLS WITH A DECREASINGG TEMPERATURE GRADIENT WITHIN THE WALLS FROM INSIDE TO OUTSIDE WHEN IIN USE, EACH MOLD WALL COMPRISING A PLATE PORTION, A FRAME PORTION INTEGRAL WITH SAID PLATE PORTION AND A PORTION HAVING SPACED RECTANGULAR COLUMNS ALSO INTEGRAL WITH SAID PLATE PORTION, SAID FRAME PORTION SURROUNDING SAID COLUMN PORTION AND EXTENDING OUTWARDLY FROM SAID PLATE PORTION AND DISTANCE APPROXIMATERLY 4 TIMES AS GREAT AS THE THICKNESS OF SAID PLATE PORTION, SAID COLUMN PORTION EXTENDING OUTWARDLY THE SAME DISTANCE ANND COMPRSIIGN A PLURALITY OF RECTANGULAR COLUMNS POSITIONED IN VERTICAL AND HORIZONTAL ROWS SPACED FROM EACH OTHER A DISTANCE WHICH IS ABBOUT ONE-FIFTH THE THICKNESS OF SAIDD PLATE PORTION, THE SPACING BETWEEN SAID COLUMNS BEING SUCH THAT COOLING WATER COULDD HARDLY CIRCCULATE THEREIN EVEN IF SAID SPACINGWERE NOT FILLED WITH SOLID MATERIAL, SAID SPACING BEING FILLED WITH A SOLID YIELDING HEAT RETAINING MATERIAL; WHEREBY THE TEMPERATURE GRADIENT ACROSS THE INSIDE TO OUTSIDE DIMENSION OF THE MOLD WALL REMAINS SUBSTANTIALLY CONSTANT AND SAID YIELDING MATERIAL ABSORBS DEFORMATIONS IN SAID COLUMNS DUE TO THE TEMPERATURE GRADIENT INN THE MOLD WALL THEREBY STOPPING DEFORMATIONS FROM ACCUMULATING FROM ONE COLUMN TO ANOTHER AND FROM ONE PART OF THE MOLD WALL TO ANOTHER. 